Non-homogeneous Mixture Research Articles

Effects of Defects on the Properties of Polymer Nanocomposites: A Brief Review

AbstractPolymer nanocomposites are promising materials for various applications in the electronics, biomedicine, and aerospace industries. However, the fabrication errors or defects, e.g., induced porosity, significantly impact the performance and the reliability of devices fabricated from polymer nanocomposites. Hence, this study has comprehensively carried out an investigation into the effects of defects on the properties of photovoltaic active cells, biomimetic scaffold, and aircraft structures that are fabricated by using polymer nanocomposites. Agglomeration is another defect that degrades the intended properties of polymer nanocomposite devices. For photovoltaic devices, defects can be controlled by the selective modification of organic semiconductor molecular structures. In addition, proper optimization of the process parameters and the material selection, are effective approaches for obtaining excellent photovoltaic cells. Furthermore, the presence of impurities, a non-homogeneous mixture of organic and inorganic materials, and the incomplete solubility of nanoparticles, are detrimental factors that affect the cell proliferation performance of biomimetic scaffolds. These technological imperfections must be also avoided when producing parts for aircraft structures. In other words, impurities introduced during the synthesis or processing stages can lead to irregularities in the material structure, which often affect its mechanical, electrical, biomedical, and optical properties. The understanding and mitigating of these factors are crucial for the optimization of the properties and performance of polymer nanocomposites in various applications.

Viscosity Analysis of Copper Aluminium Manganese (CuAlMn) Shape Memory Alloy Mixed with Polyethylene Glycol (Peg), Polymethyl Methacrylate Acrylic (Pmma) and Stearic Acid (Sa) Based Binder

Shape memory alloys (SMAs) are a class of smart materials that have the unusual feature of remembering the initial shape after plastic deformation. SMAs differ from traditional elastic/plastic materials in because of reversible hysteretic thermos mechanical behavior. Copper (Cu) based shape memory alloys are the most promising in terms of practical application due to their inexpensive cost and high recovery force. Powder injection molding (PIM) is well known for the creation of complex components (micro parts) and Copper Aluminium Manganese (CuAlMn) materials are studied through this process. The rheological behavior of the feedstock needs to be determined to avoid any nonhomogeneous mixture between powder and binder that may result in powder and binder separation during the injection molding process. This work focused on the rheological properties of CuAlMn with a binder system of polyethylene glycol (Peg), polymethyl methacrylate acrylic (Pmma) and stearic acid (Sa). The critical powder volume percentage of composite was at 85wt% Cu, 12wt% Al and 3wt% Mn was obtained. Based on such value, the powder loadings used in this work was 58wt% mixed with 73wt% Peg, 12wt% Pmma and 5wt% Sa. A capillary rheometer was employed for the rheological studies where the relationship between shear rate and viscosity was investigated. There were 3 variant temperatures (115℃, 125℃ and 135℃) and 4 loads (40N, 50N, 60N and 70N) applied for the rheology test. The obtained result shows that the overall shear rate and viscosity are within the PIM process recommended range and flow index is below 1. This shows pseudoplastic behavior of the feedstock.

Effect of Injection Timing on the Dual Fuel Engine Performance Operated with Hydrogen and Nano-Biodiesel Blends

In the current work, effect of nano-biodiesel blends and injection timing on the performance of hydrogen fueled dual fuel (DF) engine is presented. Hydrogen flow rate is maintained constant with a flow rate of 0.15 kg/h. For this B20 and nano-blends of Nigella sativa oil methyl ester (NLSTVAOME) and Jack fruit seed oil methyl ester (JKFSOME) fuel combinations are used. Nano-blends of respective B20 biodiesels are prepared using graphene amine (GA) nanoparticles with varied proportions ranging from 60 to 100 ppm using probe sonication method. Stabilization of the nano-blends are ensured with reference to quantity of nanoparticle, surfactant SDS (Sodium Dodecyl Sulfate) used and sonication time. Addition of the nanoparticles in the B20 biodiesel blends till 80 ppm showed considerable improvements on the performance of diesel engine with single fuel operation due to improved combustion compared to B20 biodiesel blends. Beyond 80 ppm the performance deteriorated due to non-homogeneous mixtures of nano-biodiesel blends. Injection timing (IT) for the modified DF engine IT is varied from 19 to 31oBTDC in steps of 4oBTDC. Further advancing the IT from 19 to 27oBTDC showed improved dual fuel engine performance with B20+GA80 blends of both biodiesels along with hydrogen induction when compared to B20 operation. Further mixing of air-hydrogen in the inlet manifold of dual fuel engine is studied using CFD analysis for varied hydrogen flow rates ranging from 0.10 to 0.2 kg/h in steps of 0.05 kg/h.

HetMM: A Michaelis-Menten model for non-homogeneous enzyme mixtures

HetMM: A Michaelis-Menten model for non-homogeneous enzyme mixtures

Thickened Flame LES methodology for turbulent propagating flames in non-homogeneous mixtures: application to a constant volume chamber

A Large Eddy Simulation methodology is presented in the framework of the Thickened Flame model, to predict the dynamics of turbulent propagating flames in non-homogeneous mixtures at variable pressure and temperature. At first, an analytical model is introduced to evaluate dilution by burnt gases and correct the chemical scheme. This method is then coupled with a new combustion model (the Stretched-Thickened Flame model or S-TF) allowing to capture stretch effects on thickened flame fronts. The S-TF model is also extended to accommodate multiple gas conditions. This numerical approach is applied to simulate multiple cycles of the pistonless constant volume combustion (CVC) chamber CV2, operating at the Pprime laboratory in Poitiers, France. The experimental ignition sequence and flame propagation is taken as reference. Results demonstrate the capability of this model to predict flame evolution in the CVC chamber. Comparisons with the classical Thickened Flame model underscore the effectiveness of the S-TF model, also for turbulent flames.

Development of a low-medium temperature T-history setup for the thermal storage characterization of non-homogeneous mixtures containing PCMs

More attention has been paid to thermal energy storage in recent years for its advantages in heating and cooling applications to foster the use of renewable energies. As part of the design of new thermal energy storage materials, the characterization of specific heat capacity and phase change enthalpy is required. One of the most widespread methods for evaluating specific heat capacity and phase change enthalpy is differential scanning calorimetry (DSC). However, the small amount of required material means that DSC is not the most suitable method for non-homogeneous materials. This paper presents the development and validation of a low-medium temperature (<100 °C) T-history system for measuring specific heat capacity and phase change enthalpy as an economical alternative. Validation was carried out with paraffins used as phase change material and two data processing methods were applied. Only one of the methods was able to measure the specific heat capacity in the liquid and solid phases, and the phase change enthalpy. Acceptable deviations calculated as the relative error in relation to DSC and manufacturer values were obtained with values lower than 18.50 % and 14.58 % respectively. The new system was used to evaluate the thermal properties of a pure paraffin/water emulsion and a hybrid carbon-paraffin/water emulsion by corroborating its suitability for measuring non-homogeneous samples.

New coefficients of the weighted-sum-of-gray-gases model for gas radiation characteristics of hydrogen/natural gas blends combustion

To achieve carbon neutrality, hydrogen/natural gas blends are gaining momentum as a clean low-carbon fuel for the future. In order to accurately carry out the CFD numerical simulation of hydrogen/natural gas blends combustion, it is imperative to establish a precise model for gas radiation characteristics. The existing weighted-sum-of-gray-gases model (WSGGM) is not suitable for high hydrogen content fuels, such as hydrogen/natural gas blends. Hence, new coefficients of WSGGM is formulated specifically for the combustion of hydrogen/natural gas blends, drawing upon the groundwork established by the statistical narrow-band model (SNB model). This model is specifically designed to be applicable within the ambient pressures, encompassing the temperature regime of 400–2500 K, a path-length range of 0.001–60 m, and a hydrogen blending ratio of 20%–70%. The radiative heat transfer characteristics of the sum of the molar fraction of H2O and CO2 at 0.9, 0.6, and 0.3 were studied according to application conditions. The WSGGM is implemented to compute the radiative heat transfer in non-isothermal and non-homogeneous gas mixtures. When compared to the benchmark model, the deviation of the wall heat flux does not surpass 5.20%. The results demonstrate the excellent adaptability of the WSGG coefficients in simulating the radiative heat transfer during hydrogen/natural gas blends combustion.

Falkner-Skan aspects of a radiating (50% ethylene glycol + 50% water)-based hybrid nanofluid when Joule heating as well as Darcy-Forchheimer and Lorentz forces affect significantly

Falkner-Skan aspects are revealed numerically for a non-homogeneous hybrid mixture of 50% ethylene glycol-50% water, silver nanomaterials Ag, and molybdenum disulfide nanoparticles MoS2 during its motion over a static wedge surface in a Darcy-Forchheimer porous medium by employing the modified Buongiorno model. The Brownian and thermophoresis mechanisms are included implicitly along with the thermophysical properties of each phase via the mixture theory and some efficient phenomenological laws. The present simulation also accounts for the impacts of nonlinear radiative heat flux, magnetic forces, and Joule heating. Technically, the generalized differential quadrature method and Newton-Raphson technique are applied successfully for solving the resulting nonlinear boundary layer equations. In a limiting case, the obtained findings are validated accurately with the existing literature outcomes. The behaviors of velocity, temperature, and nanoparticles volume fraction are discussed comprehensively against various governing parameters. As crucial results, it is revealed that the temperature is enhanced due to magnetic field, linear porosity, radiative heat flux, Brownian motion, thermophoresis, and Joule heating effects. Also, it is depicted that the hybrid nanoliquids present a higher heat flux rate than the monotype nanoliquids and liquids cases. Moreover, the surface frictional impact is minimized via the linear porosity factor. Furthermore, the surface heat transfer rate receives a prominent improvement due to the radiative heat flux inclusion.

Combining thiol-ene coupling and transesterification as the route for bio-based hyperbranched dendritic compounds: Model reactions study

The aim of this work was to develop strategies for the synthesis of dendritic macromolecules from raw materials obtained through the chemical modification of vegetable oils. Plant oils containing unsaturated fatty acids are a potential source of the ω-esters of various fatty acids as they can be obtained via metathesis using ethylene, proceeded with transesterification using methanol resulting in the formation of the i.e. methyl 9-decenoate. Methyl 10-undecenoate (MU), as a model substrate representing ω-esters of the methyl carboxylic acids, together with 1-thioglycerol (TG) as the multifunctional thiol compound, and pentaerythritol (PE) as the core were chosen for the investigated synthesis of the hyperbranched polymers using the divergent method. The “click” thiol-ene coupling turned out to be the efficient and selective reaction of MU and TG leading to the highly pure product (MUTG) without any further purification. The dendritic structure based on MUTG, used in excess referring to pentaerythritol, synthesized via transesterification resulted in a non-homogeneous mixture of the products exhibiting different degrees of branching and distinct molecular weights (Mn ranged from 1479 to 3446 g/mol; Đ = 1.01–1.03). It was found that the stoichiometric relation of the reagents (excess of the MUTG) enables control of the reaction course and branching progress due to the specific content of the primary and secondary hydroxyl groups in the reaction mixture: degree of branching was determined only for the biggest molecule with Mn = 3446 g/mol (D = 1.01; DOB = 1), whose second generation dendrimeric structure was confirmed by the 1H and 13C-NMR spectroscopy.

A non-nuclear inline densitometer for multiphase flows

Multiphase flowmeters are used in the oil-and-gas industry to measure real-time flow rates of oil, gas, and brine, flowing simultaneously as a non-homogeneous mixture, in a pipeline from wellhead to separator. Since these flow rates cannot be measured directly, they are inferred from other measurements including mixture density. Mixture density is commonly measured using nuclear densitometers which can be problematic in terms of safety and maintenance. This paper details the development—concept and experimental validation—of a non-nuclear inline densitometer that measures multiphase mixture density using pressure sensors. A comprehensive flow-loop test was conducted at a commercial facility to evaluate the technology under a wide range of flow conditions—flow rates 1000 to 10000 bpd, gas fractions 0% to 96%, water cuts 0% to 100%, with a synthetic oil as liquid hydrocarbon, methane as gas medium, two water salinities—totaling nearly 300 test points. The results from this experimental validation—specifically, the technology’s accuracy and operating envelope—point to a groundbreaking practical solution to a long-standing problem.

Accurate modeling of blood flow in a micro-channel as a non-homogeneous mixture using continuum approach-based diffusive flux model

This paper presents a continuum approach for the blood flow simulation, inside the micro-channel of the few micrometers characteristics dimension, within the context of the finite volume method on unstructured grids. The velocity and pressure fields, for the blood flow, are obtained here by solving the Navier–Stokes equations. A particle transport equation, based on the diffusive flux model, provides the hematocrit distribution (i.e., the red blood cells volume-fraction). The momentum conservation equation for a non-Newtonian fluid model is coupled with the particle transport equation through the constitutive blood viscosity model, and this blood viscosity is dependent on hematocrit and shear rate. The continuum approach for blood flow inside the micro-channel of the length scale of a few micrometers to a few hundred micrometers is expected to break down. Interestingly, the present approach provides meaningful insights into biophysics with less computational cost and shows a good match with the experiments and mesoscale simulation with a maximum average deviation of 11% even at the characteristic dimensions of 10–300 μm. A correlation is proposed for additional-local shear rate in terms of the hematocrit and the ratio of red blood cells diameter to the channel diameter, which helps us to demonstrate an increase in the accuracy and also eliminates the issues of unphysical hematocrit reported in the earlier studies available in the literature. The study is extended to provide new results inside a square and rectangular cross section micro-channels, under a range of inlet parameters.

Ambient Hot Box: An Instrument for Thermal Characterization of Building Elements and Constructive Materials.

In assessing the energy performance of buildings, the thermal performance of the structural components and building materials is crucial. Although reference catalogs are used to determine the thermal properties of construction materials, the use of novel materials or non-homogeneous mixtures, particularly with biomaterials, demands the development of new instruments that are capable of performing rapid, accurate and cost-effective thermal characterization. This study introduces the ambient hot-box, a new tool for measuring the thermal properties of construction components and heterogeneous materials. The paper provides a methodology for measuring a sample's benchmark and fresh materials using a streamlined hot-box-based instrument. Utilizing samples as a benchmark material, the new instrument is assessed, yielding transmittance values with errors below 4%. The electronic circuits, measurements techniques and instrument implementation are all described.

A wide-band based weighted-sum-of-gray-gases model for participating media: Application to [formula omitted]-[formula omitted] mixtures with or without soot

The presence of participating gases and soot in combustion processes often makes the thermal radiation the main mechanism of heat transfer due to the elevated temperatures involved. The accurate solution of the radiative transfer equation (RTE) through the line-by-line (LBL) integration in engineering applications is in general still impracticable due to the high computational effort required to account for the millions of spectral lines that characterize the absorption coefficient of a gas. Global spectral models, such as the weighted-sum-of-gray-gases (WSGG) model, are attempts to replace the LBL integration with low computational cost and satisfactory accuracy. In the present study, an improvement of the WSGG model through a partition of the spectrum is proposed. The spectrum is divided into a set of ranges in which the standard methodology of the WSGG model is applied to determine the gray gases coefficients in these bands. This is the central aspect of what is named here a wide-band based WSGG (WBW) model, which consists firstly of determining the emittance of each band from the HITEMP 2010 database, then obtaining the pressure-absorption coefficients and the temperature-dependent coefficients. The total radiative heat flux and radiative heat source are obtained by the summation of the contribution of each band individually. For soot, a gray gas approach is considered for each band via Planck-mean absorption coefficients. A set of 1D problems consisting of two infinite parallel black walls, filled with a non-isothermal and non-homogeneous gaseous mixture of water vapor, carbon dioxide and soot, is solved. The results show that, especially in cases where the thermal radiation of soot is dominant, the maximum deviations obtained with the proposed method in relation to the LBL solution reduce by almost three times compared to other global WSGG models in the literature, in addition to decreasing by 40% the number of equations that need to be solved.

Dry Syrup: A Comprehensive Review

The oral dosage forms are most popular because of their ease of administration, patient compliance, and formulation stability. Tablets and capsules, the most popular oral dosage form, have the drawback of difficulty swallowing the dosage form specially developed for pediatric and geriatric patients. In recent times the, modern scientific and technological advancement in pharmaceutical field has created a bank of interest in the reconstitutable oral suspension (Dry syrup). Dry syrups are the dry mixtures that require adding water at the dispensing time. Dry syrups show adequate chemical stability of drug during shelf life and reduce the final product's weight. Moreover, dry syrups show higher bioavailability than tablets and capsules as they disintegrate in water outside the oral cavity and directly enter the gastrointestinal tract. Most of the drugs prepared as dry powders for oral suspensions are antibiotics. The present review gives an account of the excipients used, methods of preparation of dry syrup, their evaluation, and their packaging. When manufacturing dry syrup medicine, the dry mixture should have a uniform concentration of the required ingredients. This ensures that the drug does not break up into a non-homogeneous mixture when reconstituted, which may lead to errors in dosage. The items used in the manufacturing of dry syrup include excipients, granule disintegrating, granule binder and powder blends. Excipients are used to stabilize active ingredients for a long period. The type of excipient used is based on the suitability for reconstitution and the type of the powder the granule disintegrate helps ensure the dry syrup particles do not aggregate during reconstitution. The granule binder helps ensure that the dry syrup's particles settle in the suspension.

Mechanistic insights into Fe(II)-citric acid complex catalyzed CaO2 Fenton-like process for enhanced benzo[a]pyrene removal from black-odor sediment at circumneutral pH

Polycyclic aromatic hydrocarbons (PAHs) are found ubiquitously in contaminated aquatic sediments. They are difficult to degrade, particularly the high-molecular-weight PAHs (e.g., benzo[a]pyrene, BaP). In this study, CaO2 assisted with ferrous ion (Fe(II))-citric acid (CA) was applied for the first time in BaP degradation in aquatic sediment. Among the treatment processes we studied, CaO2/Fe(Ⅱ)/CA could effectively degrade BaP at circumneutral pH (7.0 ± 0.3), reaching a maximum of nearly 80% under optimal conditions (0.84 mM CaO2, 0.21 mM Fe(Ⅱ), and 0.35 mM CA in per gram of dry sediment). Contrary to some external environmental factors such as temperature, common metal ions, and natural organic matters, a certain amount of moisture content and inorganic anions (Cl−, SO42−) exhibited a positive effect on BaP degradation, which can probably be contributed to the improved mass transfer rate in the non-homogeneous sediment-water mixture and a higher level of free radicals. The degradation kinetic dominated by hydroxyl radicals included three main stages contribution ∼29.4%, ∼43.1%, and ∼2.4% to BaP degradation, respectively. Based on the theoretical calculations of density functional theory, a pathway for BaP degradation was proposed. For the treatment of actual contaminated sediment, the CaO2/Fe(II)/CA process could realize the elimination of black-odor and effective removal of PAHs from the sediment, as well as negligible ecotoxicity on benthic organisms. This study provides a reference and guidance for the use of CaO2 based Fenton-like systems in treating PAH-contaminated black-odor river sediments.

Red blood cells tracking and cell-free layer formation in a microchannel with hyperbolic contraction: A CFD model validation

Background and ObjectiveIn recent years, progress in microfabrication technologies has attracted the attention of researchers across disciplines. Microfluidic devices have the potential to be developed into powerful tools that can elucidate the biophysical behavior of blood flow in microvessels. Such devices can also be used to separate the suspended physiological fluid from whole in vitro blood, which includes cells. Therefore, it is essential to acquire a detailed description of the complex interaction between erythrocytes (red blood cells; RBCs) and plasma. RBCs tend to undergo axial migration caused by occurrence of the Fåhræus-Lindqvist effect. These dynamics result in a cell-free layer (CFL), or a low volume fraction of cells, near the vessel wall. The aim of the paper is to develop a numerical model capable of reproducing the behavior of multiphase flow in a microchannel obtained under laboratory conditions and to compare two multiphase modelling techniques Euler-Euler and Euler-Lagrange. MethodsIn this work, we employed a numerical Computational Fluid Dynamics (CFD) model of the blood flow within microchannels with two hyperbolic contraction shapes. The simulation was used to reproduce the blood flow behavior in a microchannel under laboratory conditions, where the CFL formation is visible downstream of the hyperbolic contraction. The multiphase numerical model was developed using Euler-Euler and hybrid Euler-Lagrange approaches. The hybrid CFD simulation of the RBC transport model was performed using a Discrete Phase Model. Blood was assumed to be a nonhomogeneous mixture of two components: dextran, whose properties are consistent with plasma, and RBCs, at a hematocrit of 5% (percent by volume of RBCs). ResultsThe results show a 5 μm thick CFL in a microchannel with a broader contraction and a 35 μm thick CFL in a microchannel with a narrower contraction. The RBC volume fraction in the CFL is less than 2%, compared to 7–8% in the core flow. The results are consistent for both multiphase simulation techniques used. The simulation results were then validated against the experimentally-measured CFL in each of the studied microchannel geometries. ConclusionsReasonable agreement between experiments and simulations was achieved. A validated model such as the one tested in this study can expedite the microchannel design process by minimizing the need to prefabricate prototypes and test them under laboratory conditions.

Numerical simulation of a thermally enhanced EMHD flow of a heterogeneous micropolar mixture comprising (60%)-ethylene glycol (EG), (40%)-water (W), and copper oxide nanomaterials (CuO)

In the past decades, the thermal and rheological properties of nanofluids have attracted much attention from many investigators due to their numerous applications as promising enhanced working fluids. The present numerical analysis intended to evidence the main hydro-thermal and mass transport appearances featuring the convective flows of an exceptional non-homogeneous micropolar mixture (i.e., 60% of ethylene glycol, 40% of pure water, and copper oxide nanomaterials) over an impermeable horizontal electromagnetic surface (i.e., Riga plate), which is heated convectively in the presence of a particular variable heat source. For this purpose, several admissible physical theories and hypotheses are adopted herein to derive the foremost conservation equations based on the renovated Buongiorno's formulation and some more realistic boundary conditions. Further, the leading partial differential equations (PDEs) are transformed into a system of ordinary differential equations (ODEs), which are tacked thereafter numerically using an efficient GDQNRM procedure. After performing multiple validations with the recent literature results, the aspects of the studied EMHD convective micropolar nanofluid flow are spotted accordingly and then discussed comprehensively via multiple figures and tables. As prominent results, it is found that the micropolarity and electrically conducting trends of the nanofluidic medium play an important role in the hastening of the nanofluid motion. Also, it is explored that the thermally enhancing influence of the thermophoresis diffusive mechanism can be reinforced more by the existence of an internal heat source along with an appropriate convective heating process.

Experimental testing of the effectiveness of novel hydrocyclones for separation of impurities in biofuels

This paper investigates the potential sources of renewable energy, in particular biofuels. Biofuels tend to contain multiple harmful impurities that need to be separated if the biofuel is to have good energy performance, and the systems that run on it to produce electricity or heat are to operate more reliably. The paper discusses use of hydrocyclones as the most productive and reliable biofuel purification method. It dwells upon the factors that negatively affect separation of mixtures in a hydrocyclone, which are attributable to the complex hydrodynamics of the flow in such a unit. In order to eliminate these factors, the authors hereof have developed two hydrocyclone designs. An experimental test bench was designed and made to test these designs. Parts of the units were 3D printed from an environmentally friendly material. For testing, we used a biodiesel made from waste cooking oil with an impurity content of 23%. Experiments showed a maximum separation rate of 94.2%. The proposed solutions did improve the effectiveness of biodiesel mixture separation. These designs can be effectively used to separate non-homogeneous mixtures.

Numerical solutions of radiative heat transfer in combustion systems using a parallel modified discrete ordinates method and several recent formulations of WSGG model

The aim of the paper is to perform 3D radiative transfer calculations in combustion gas mixtures. For this purpose, a parallel modified Discrete Ordinates Method with a cell-vertex formulation on unstructured tetrahedral grid is proposed for solving the Radiative Transfer Equation (RTE) in realistic geometries. Several recent formulations of the weighted-sum-of-gray-gases (WSGG) model are implemented. To reduce the false scattering, the cell-vertex formulation is combined with an Exponential scheme and is compared to the Step scheme. The results are then compared with published results on non-isothermal and non-homogeneous gas mixtures. The use of non-gray WSGG models shows a very good level of accuracy for the evaluation of wall heat transfer and radiative heat source. The Exponential scheme is more accurate than the Step scheme. The summation over the wavenumber spectrum of the radiative model is usually carried out after having computed the radiative quantities for each discrete angular direction. By summing first over the wavenumber spectrum, a reduction in the computation time is significantly obtained, up to a factor of 16 on a case study. Also, additionnal significant speedup is obtained with an efficient distributed and multi-threaded parallel algorithm. When the Step scheme is used, the computation time increases very slightly with the number of gray gases. The procedure to speed up the calculations can be applied to any arbitrary numerical method for solving the spectral RTE.

Improvement of the efficiency of the superposition method applied to the WSGG model to compute radiative transfer in gaseous mixtures

A new method for the treatment of radiative heat transfer in mixtures of participating species in the framework of the weighted-sum-of-gray-gases (WSGG) model is proposed, based on a modification of the existing superposition method. This new approach allows for a reduction in the number of times that the WSGG radiative transfer equation must be solved by decreasing the total number of gray gases that needs to be considered for modeling the mixture. Although it may be extended to mixtures of any number of species, in this paper the new method is only applied to water vapor-carbon dioxide mixtures. The reference for the comparisons is provided by line-by-line (LBL) integration of absorption spectra generated from a high-resolution spectral database. Results show that the method does not yield a loss in accuracy relative to the standard superposition method, and performs better than an existing WSGG model developed for H2O−CO2 mixtures with varying mole fraction ratio. There is also a reduction of about 50% in the computational time required for the solution compared to the original superposition method, thus making the new method more efficient and more competitive in relation to other methodologies for modeling radiative transfer in non-homogeneous mixtures.